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MARTINEZ, California (CNN) -- Investigators have arrested a 16-year-old boy in connection with the killing of Pamela Vitale, wife of high-profile attorney and television legal analyst Daniel Horowitz, a sheriff's spokesman said Thursday.

The suspect is from Lafayette, California, where the couple were building their dream house in the hills east of Oakland.

The teenager was arrested Wednesday night and was being held in the Contra Costa County juvenile detention facility, said Jimmy Lee, a spokesman for the Contra Costa County Sheriff's Department. (Watch a report on the arrest -- 4:35)

Investigators have not identified the boy, who has not yet been charged. Because he is a juvenile, CNN is also not identifying the suspect, who lived near the Horowitz estate.

Vitale was beaten with a piece of crown molding, and a cross was carved into her back, a law enforcement official with detailed knowledge of the case said.

According to the law enforcement official, investigators believe Vitale may have confronted the boy on her property -- and that confrontation may have led to the slaying.

"We are still trying to establish the exact motive," Lee said. Investigators would not name the youth, Lee said.

The teenager was arrested at a relative's home in the nearby town of Walnut Creek, the law enforcement official said.

Horowitz said he found Vitale, 52, when he returned from San Francisco to the mobile home where the couple lived for the past two years while building a 7,000-square-foot Italian-style mansion.

It was Vitale's dream house and she supervised the project down to the last detail, Horowitz told CNN.

Medical examiners have concluded that Vitale died from blunt trauma to the head, said a spokesman for the Contra Costa County Sheriff's Department.